FAB Defense GLR 16 CP Black Buttstock with Adjustable Cheek Riser Battery Storage - The GLR-16 Buttstock for your AR15/M16 provides you with enhanced versatility with it's stock extension and adjustable Cheek Rest. Features: Adjustable stock for AR-15/M4 Compatible with Mil-Spec and Commercial receiver extensions Sealed battery storage compartment Height-adjustable cheek rest Anti-rattle mechanism Integrated sling attachment slots